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Guillaume DRUTEL




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14 publication(s) depuis Janvier 1995:


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23/09/2018 | Exp Neurol   IF 4.5
Serotonin2B receptors in the rat dorsal raphe nucleus exert a GABA-mediated tonic inhibitory control on serotonin neurons.
Cathala A, Devroye C, Drutel G, Revest JM, Artigas F, Spampinato U

Abstract:
The central serotonin2B receptor (5-HT2BR) is a well-established modulator of dopamine (DA) neuron activity in the rodent brain. Recent studies in rats have shown that the effect of 5-HT2BR antagonists on accumbal and medial prefrontal cortex (mPFC) DA outflow results from a primary action in the dorsal raphe nucleus (DRN), where they activate 5-HT neurons innervating the mPFC. Although the mechanisms underlying this interaction remain largely unknown, data in the literature suggest the involvement of DRN GABAergic interneurons in the control of 5-HT activity. The present study examined this hypothesis using in vivo (intracerebral microdialysis) and in vitro (immunohistochemistry coupled to reverse transcription-polymerase chain reaction) experimental approaches in rats. Intraperitoneal (0.16mg/kg) or intra-DRN (1muM) administration of the selective 5-HT2BR antagonist RS 127445 increased 5-HT outflow in both the DRN and the mPFC, these effects being prevented by the intra-DRN perfusion of the GABAA antagonist bicuculline (100muM), as well as by the subcutaneous (0.16mg/kg) or the intra-DRN (0.1muM) administration of the selective 5-HT1AR antagonist WAY 100635. The increase in DRN 5-HT outflow induced by the intra-DRN administration of the selective 5-HT reuptake inhibitor citalopram (0.1muM) was potentiated by the intra-DRN administration (0.5muM) of RS 127445 only in the absence of bicuculline perfusion. Finally, in vitro experiments revealed the presence of the 5-HT2BR mRNA on DRN GABAergic interneurons. Altogether, these results show that, in the rat DRN, 5-HT2BRs are located on GABAergic interneurons, and exert a tonic inhibitory control on 5-HT neurons innervating the mPFC.




24/11/2017 | cell cycle
Regulation of RNA polymerase III transcription during transformation of human IMR90 fibroblasts with defined genetic elements.
Durrieu-Gaillard S, Dumay-Odelot H, Boldina G, Tourasse NJ, Allard D, Andre F, Macari F, Choquet A, Lagarde P, Drutel G, Leste-Lasserre T, Petitet M, Lesluyes T, Lartigue-Faustin L, Dupuy JW, Chibon F, Roeder RG, Joubert D, Vagner S, Teichmann M

Abstract:
RNA polymerase (Pol) III transcribes small untranslated RNAs that are essential for cellular homeostasis and growth. Its activity is regulated by inactivation of tumor suppressor proteins and overexpression of the oncogene c-MYC, but the concerted action of these tumor-promoting factors on Pol III transcription has not yet been assessed. In order to comprehensively analyse the regulation of Pol III transcription during tumorigenesis we employ a model system that relies on the expression of five genetic elements to achieve cellular transformation. Expression of these elements in six distinct transformation intermediate cell lines leads to the inactivation of TP53, RB1, and protein phosphatase 2A, as well as the activation of RAS and the protection of telomeres by TERT, thereby conducting to full tumoral transformation of IMR90 fibroblasts. Transformation is accompanied by moderately enhanced levels of a subset of Pol III-transcribed RNAs (7SK; MRP; H1). In addition, mRNA and/or protein levels of several Pol III subunits and transcription factors are upregulated, including increased protein levels of TFIIIB and TFIIIC subunits, of SNAPC1 and of Pol III subunits. Strikingly, the expression of POLR3G and of SNAPC1 is strongly enhanced during transformation in this cellular transformation model. Collectively, our data indicate that increased expression of several components of the Pol III transcription system accompanied by a 2-fold increase in steady state levels of a subset of Pol III RNAs is sufficient for sustaining tumor formation.




05/2011 | Am J Pathol   IF 4.1
Tissue microarray cytometry reveals positive impact of homeodomain interacting protein kinase 2 in colon cancer survival irrespective of p53 function.
Soubeyran I, Mahouche I, Grigoletto A, Leste-Lasserre T, Drutel G, Rey C, Pedeboscq S, Blanchard F, Brouste V, Sabourin JC, Becouarn Y, Reiffers J, Ichas F, De Giorgi F

Abstract:
The human p53 gene is a tumor suppressor mutated in half of colon cancers. Although p53 function appears important for proliferation arrest and apoptosis induced by cancer therapeutics, the prognostic significance of p53 mutations remains elusive. This suggests that p53 function is modulated at a posttranslational level and that dysfunctions affecting its modulators can have a prognostic impact. Among p53 modulators, homeodomain interacting protein kinase (HIPK) 2 emerges as a candidate 'switch' governing p53 transition from a cytostatic to a proapoptotic function. Thus, we investigated the possible prognostic role of HIPK2 on a retrospective series of 80 colon cancer cases by setting up a multiplexed cytometric approach capable of exploring correlative protein expression at the single tumor cell level on TMA. Crossing the data with quantitative PCR and p53 gene sequencing and p53 functional assays, we observed the following: despite a strong impact on p21 transcription, the presence of disabling p53 mutations has no prognostic value, and the increased expression of the HIPK2 protein in tumor cells compared with paired normal tissue cells has a strong impact on survival. Unexpectedly, HIPK2 effect does not appear to be mediated by p53 function because it is also observed in p53-disabling mutated backgrounds. Thus, our results point to a prominent and p53-independent role of HIPK2 in colon cancer survival.




18/02/2011 | Brain Behav Immun   IF 6.3
Hormonal, hypothalamic and striatal responses to reduced body weight gain are
Pourtau L, Leemburg S, Roux P, Leste-Lasserre T, Costaglioli P, Garbay B, Drutel G, Konsman JP

Abstract:
Lack of compensatory or even reduced food intake is frequently observed in




2008 | J Cell Sci   IF 4.4
p190B RhoGAP regulates endothelial-cell-associated proteolysis through MT1-MMP and MMP2
Guegan F, Tatin F, Leste-Lasserre T, Drutel G, Genot E, Moreau V

Abstract:
The two isoforms of p190 RhoGAP (p190A and p190B) are important regulators of RhoGTPase activity in mammalian cells. Both proteins are ubiquitously expressed, are involved in the same signalling pathways and interact with the same identified binding partners. In search of isoform functional specificity, we knocked down the expression of each p190 protein using siRNA and examined the resulting phenotypic changes in human umbilical vein endothelial cells (HUVECs). We provide evidence that p190B plays a crucial role in the regulation of MT1-MMP expression and cell-surface presentation, as well as subsequent MMP2 activation. p190B is involved in both local extracellular matrix degradation at podosomes and endothelial cell assembly into tube-like structures in Matrigel. In addition, whereas p190B knockdown does not affect podosome formation, p190A knockdown increases the number of cells showing podosome structures in HUVECs. We conclude that the two p190 RhoGAP isoforms play distinct roles in endothelial cells. In addition, our data reveal an unsuspected role for p190B in the expression of the two collaborative proteases MT1-MMP and MMP2, thereby affecting matrix remodelling and angiogenesis.




06/2007 | Endocrinology   IF 4
Tyrosine Hydroxylase and Dopamine Transporter Expression in Lactotrophs from Postlactating Rats: Involvement in Dopamine-Induced Apoptosis
Jaubert A, Drutel G, Leste-Lasserre T, Ichas F, Bresson-Bepoldin L

Abstract:
Cessation of lactation causes a massive loss of surplus lactotrophs in the rat pituitary gland. The factors and mechanisms involved in this phenomenon have not yet been elucidated. Besides its inhibitory control on prolactin secretion and lactotroph proliferation, evidence suggests that dopamine (DA) may be a proapoptotic factor for lactotrophs. We therefore tested the proapoptotic effect of DA on pituitary glands from virgin, lactating, and postlactating rats. By measuring mitochondrial membrane potential loss, caspase-3 activation, and nuclear fragmentation, we show that DA induces apoptosis specifically in lactotrophs from postlactating rats. We then determined that this effect was partly mediated by the DA transporter (DAT) rather than the D(2) receptor, as corroborated by the detection of DAT expression exclusively in lactotrophs from postlactating rats. We also observed tyrosine hydroxylase (TH) expression in postlactating lactotrophs that was accompanied by an increase in DA content in the anterior pituitary gland of postlactating compared with virgin rats. Finally, we observed that cells expressing TH coexpressed DAT and cleaved caspase-3. These findings show that DA may play a role in lactotroph regression during the postlactation period by inducing apoptosis. The fact that this process requires DAT and TH expression by lactotrophs themselves suggests that it may be 'autocrine' in nature.




04/2006 | Mol Pharmacol   IF 4
Discovery of naturally occurring splice variants of the rat histamine H3 receptor that act as dominant-negative isoforms
Bakker R A, Lozada A F, van Marle A, Shenton F C, Drutel G, Karlstedt K, Hoffmann M, Lintunen M, Yamamoto Y, van Rijn R M, Chazot P L, Panula P, Leurs R

Abstract:
We described previously the cDNA cloning of three functional rat histamine H3 receptor (rH3R) isoforms as well as the differential brain expression patterns of their corresponding mRNAs and signaling properties of the resulting rH3A, rH3B, and rH3C receptor isoforms (Mol Pharmacol 59:1-8). In the current report, we describe the cDNA cloning, mRNA localization in the rat central nervous system, and pharmacological characterization of three additional rH3R splice variants (rH3D, rH3E, and rH3F) that differ from the previously published isoforms in that they result from an additional alternative-splicing event. These new H3R isoforms lack the seventh transmembrane (TM) helix and contain an alternative, putatively extracellular, C terminus (6TM-rH3 isoforms). After heterologous expression in COS-7 cells, radioligand binding or functional responses upon the application of various H3R ligands could not be detected for the 6TM-rH3 isoforms. In contrast to the rH3A receptor (rH3AR), detection of the rH3D isoform using hemagglutinin antibodies revealed that the rH3D isoform remains mainly intracellular. The expression of the rH3D-F splice variants, however, modulates the cell surface expression-levels and subsequent functional responses of the 7TM H3R isoforms. Coexpression of the rH3AR and the rH3D isoforms resulted in the intracellular retention of the rH3AR and reduced rH3AR functionality. Finally, we show that in rat brain, the H3R mRNA expression levels are modulated upon treatment with the convulsant pentylenetetrazole, suggesting that the rH3R isoforms described herein thus represent a novel physiological mechanism for controlling the activity of the histaminergic system.




01/2001 | Mol Pharmacol   IF 4
Identification of rat H3 receptor isoforms with different brain expression and signaling properties.
Drutel G, Peitsaro N, Karlstedt K, Wieland K, Smit MJ, Timmerman H, Panula P, Leurs R

Abstract:
We identified the cDNAs of three functional rat H3 receptor isoforms (H3A, H3B, and H3C) and one nonfunctional truncated H3 receptor (H3T). The H3A, H3B, and H3C receptor isoforms vary in the length of their third intracellular loop; the H3B and H3C receptor lack 32 and 48 amino acids, respectively. Transient expression of the H3A, H3B, and H3C receptors in COS-7 cells results in high affinity binding for the H3 antagonist [125I]iodophenpropit, which is displaced by selective H3 agonists and antagonists. The three isoforms differentially couple to the Gi protein-dependent inhibition of adenylate cyclase or stimulation of p44/p42 mitogen activated protein kinase (MAPK), a new signaling pathway for the H3 receptor. Whereas the H3A receptor was less effective in inhibiting forskolin-induced cAMP production compared with the H3B or H3C receptor, this isoform was more effective in the stimulation of p44/p42 MAPK. The H3 receptor isoforms also displayed differential CNS expression in key areas involved in regulation of sensory, endocrine, and cognitive functions. A differential H3 receptor isoform expression was seen in, for example, hippocampus, where a characteristic dorsoventral distribution was revealed. Differential H3 receptor expression was also characteristic for the cerebellum, indicating possible histaminergic regulation of motor functions. The identification of these new H3 receptor isoforms and their specific signaling properties adds a new level of complexity to our understanding of the role of histamine, and the H3 receptor in brain function. The heterogeneous distribution of the isoforms suggests that H3 receptor isoform-specific regulation is important in several brain functions.




10/2000 | Eur J Neurosci   IF 2.8
Two splice variants of the hypoxia-inducible factor HIF-1alpha as potential dimerization partners of ARNT2 in neurons.
Drutel G, Kathmann M, Heron A, Gros C, Mace S, Schwartz JC, Arrang JM

Abstract:
The hypoxia-inducible factor (HIF-1alpha), a basic helix-loop-helix transcription factor, is known to heterodimerize with ARNT1, a nuclear translocator, to trigger the overexpression in many cells of genes involved in resistance to hypoxia. Although HIF-1alpha and ARNT1 are both expressed in brain, their cellular localization and function therein are unknown. Here, using in situ hybridization and immunocytochemistry, we show that HIF-1alpha is expressed in normoxic cerebral neurons together with not only ARNT1 but also ARNT2, a cerebral translocator homologous to ARNT1 but displaying, unlike ARNT1, a selective neuronal expression. In contrast, other potential partners of the translocators, i.e. the aryl hydrocarbon receptor (AHR) and the single-minded protein 2 (SIM2), are not expressed in the adult brain. We also identify two splice variants of HIF-1alpha in brain, one of which dimerizes with ARNT2 even more avidly than with ARNT1. The resulting heterodimer, in contrast with the HIF-1alpha/ARNT1 complex, does not recognize the HIF-1-binding site of the hypoxia-induced erythropoietin (Epo) gene, suggesting that it controls transcription of a distinct set of genes. We therefore propose that HIF-1alpha and ARNT2 function as preferential dimerization partners in neurons to control specific responses, some of which may not be triggered by hypoxia. In support of this proposal, in nonhypoxic PC12 cells constitutively coexpressing HIF-1alpha, ARNT1 and ARNT2, downregulation of either HIF-1alpha or ARNT2, obtained with selective antisense nucleotides, resulted in inhibition of [3H]thymidine incorporation.




05/1999 | Eur J Neurosci   IF 2.8
ARNT2, a transcription factor for brain neuron survival?
Drutel G, Heron A, Kathmann M, Gros C, Mace S, Plotkine M, Schwartz JC, Arrang JM

Abstract:
The processes responsible for the limited ability to divide and long survival of neurons are not well understood but may involve aryl hydrocarbon receptor nuclear translocator 2 (ARNT2), a recently identified protein, apparently belonging to the basic helix-loop-helix superfamily of transcription factors, which is expressed almost exclusively in brain during the whole lifetime. In agreement, we show, in the rat, that ARNT2 immunoreactivity could be observed only within nuclei of brain neurons and of dividing and neuronal PC12 cells, a localization consistent with a role in transcription regulation. Cell death elicited either by focal ischaemia in brain or oxidative stress in PC12 cells was largely preceded by an almost complete suppression of ARNT2 expression. In contrast, when PC12 cell cycle progression was impaired, ARNT2 expression was enhanced. Finally, the downregulation of ARNT2 levels induced by antisense oligonucleotides prevented PC12 cell proliferation and induced apoptosis. These observations support the hypothesis that ARNT2 is a neuronal transcription factor, regulating cell cycle progression and preventing cell death, whose sustained expression might ensure brain neuron survival.